Background: Because adult ADHD is often accompanied by psychiatric comorbidities, the diagnostic process should include a thorough investigation for comorbid disorders. Asperger-Syndrome is rarely reported in adult ADHD and commonly little attention is paid to this possible comorbidity.
Subjects and methods: We investigated 53 adult ADHD-patients which visited our out patient clinic for first ADHD-diagnosis (17 females, 36 males; range of age: 18-56 years) for the frequency of a comorbid Asperger-Syndrome. Diagnosis of this autism-spectrum disorder was confirmed by applying the appropriate DSM-IV-criteria. Additionally we tested the power of the two screening-instruments "Autism-spectrum quotient" (AQ) and "Empathy quotient" (EQ) by Baron-Cohen for screening Asperger-Syndrome in adult ADHD.
Results: Eight ADHD-patients were diagnosed with a comorbid Asperger-Syndrome (15.1%). The difference in AQ- and EQ-scores between pure ADHD-patients and comorbid patients was analysed, showing significantly higher scores in AQ and significant lower scores in EQ in comorbid patients.
Conclusions: Results show that the frequency of Asperger-Syndrome seems to be substantially increased in adult ADHD (versus the prevalence of 0.06% in the general population), indicating that investigators of adult ADHD should also be attentive to autism-spectrum disorders. Especially the AQ seems to be a potential screening instrument for Asperger-Syndrome in adult ADHD-patients.